Figure 2. Preparation and activity analysis of PEGylated FGF2 conjugates. (A ) Synthetic route of site-specific PEGylation using mPEG-Maleimide (mPEG-MAL, 5kDa). (B ) Schematic representation of three FGF2 conjugates resulted from PEGylation, including PEG-FGF2F17C (5 ), PEG-FGF2C87A (6 ) and PEG-FGF2K129C (7 ). (C ) SDS-PAGE analysis of these PEG-FGF2 conjugates and native FGF2 under the optimal conditions. (D ) Immunoblotting analysis of p-ERK1/2 and ERK1/2 levels in HUVECs after stimulation with PEG-FGF2 conjugates and FGF2 (10 ng·mL-1). ERK and GAPDH were used as the loading controls (n = 3). (E ) Quantitative analysis of p-ERK1/2 in the indicated groups. Data are displayed as means ± SEM.**P < 0.01,***P < 0.001 vs. control group;#P < 0.05,##P < 0.01 vs. FGF2 group.